//浮点数相加
function dcmAdd(arg1,arg2){
    var r1,r2,m;
    try{r1=arg1.toString().split(".")[1].length;}catch(e){r1=0;}
    try{r2=arg2.toString().split(".")[1].length;}catch(e){r2=0;}
    m=Math.pow(10,Math.max(r1,r2));
    return (dcmMul(arg1,m)+dcmMul(arg2,m))/m;
}
// 浮点数相减
function dcmSub(arg1,arg2){
     return dcmAdd(arg1,-arg2);
}
// 浮点数相乘
function dcmMul(arg1,arg2){
    var m=0,s1=arg1.toString(),s2=arg2.toString();
    try{m+=s1.split(".")[1].length;}catch(e){}
    try{m+=s2.split(".")[1].length;}catch(e){}
    return Number(s1.replace(".",""))*Number(s2.replace(".",""))/Math.pow(10,m);
}
// 浮点数除
function dcmDiv(arg1,arg2){
    return arg1/arg2;
}
Number.prototype.add = function (arg){
                   return dcmAdd(this, arg);
}
Number.prototype.sub = function (arg){
                   return dcmSub(this, arg);
}
Number.prototype.mul = function (arg){
                   return dcmMul(this, arg);
}
Number.prototype.div = function (arg){
                   return dcmDiv(this, arg);
}